1. Field of the Invention
The present invention relates to cathodic protection clamps and more particularly relates to a clamp apparatus for securing cathodic protection to the leg portions of an offshore marine drilling platform.
2. General Background and Prior Art
In the industry of offshore drilling, one of the most important factors in maintaining the life of the rig platform is to attempt to prevent the legs of the rig platform from corroding through due to the action of the salt sea water. The most successful is to utilize a single or double zinc anode on the platform leg which through the process of electrolysis, transferred in the corrosive process to the platform leg would be transferred to the zinc anode, thus extending the life of the leg.
In order to secure the anode apparatus, there is presently utilized a metallic ring section which hinges around the leg of the platform in a clam effect, opening in half circular or quarters. The metallic encasement must then be brought together around the circumference of the pipe and welded or bolted in place. Through this method of securing single or double anodes onto the pipe leg, one can readily ascertain that the effort involved in moving the sections of the pipe clamp around the first pipe in order to encase it requires extreme labor and those instances where the pipe being encased is on the elevated platform in a marine environment. What is required is that the diver must, in effect, move the sections of the pipe clamp in position to be welded in the closed encased position around a first pipe. The size of the primary pipe often times requires 24 to 36 inch diameters, taking extreme effort in order to move the huge joints into position for clamping so that the single or double anode sections may be placed upon the leg of the platform.
Another problem in utilizing the present state of the art, is the fact that pipe clamp sections must be moved out into marine environment via transport boats, such boats having to go out sometimes over 100 miles offshore in order to reach the offshore platforms. Even with the very large boats, due to the huge size of prior art devices, a limited number of devices may be carried at one time when including the tools necessary to secure them against the rig leg and the divers who must perform the work.
A rig platform, depending on its size, may use on the order of one hundred (100) anode clamps for proper cathodic protection. It may then take numerous trips by the transport boat and excessive amounts of time in order to finally get a platform properly protected against saltwater corrosion.
Another prior art problem involves the encrustation of marine growth on offshore platform leg portions such as barnacles and their requisite removal before clamps can be affixed. The prior art type U-clamps or U-bolts are factory sized and standardized to affix to a round pipe when the pipe is clean and uniformly cylindrical in its shape. This unfortunately is not the way many existing platform legs are shaped due to the encrustations, as marine growth, barnacles, seaweed or like which grow on the platform legs particularly in the splash zone area. The encrustations add diameter to the legs or piling or risers as the case may be, making U-bolts or U-clamps not properly fit since such bolts or clamps are usually selected by inspecting construction drawings or platform specifications based upon leg or pipe sizes as when constructed.
The prior art has dealt with the problem of encrustations at the splash zone by mechanically removing the encrustations at a spot on the platform leg where the anode assembly would be desirably attached. Prior art methods such as scraping, chipping and like manual mechanical removal has been used employing divers or like offshore workers.
The present invention solves these prior art problems and shortcomings in a simple, inexpensive manner. The present invention provides an adjustable clamp assembly providing a U-shaped channel for fitting against the surface of, for example, the platform leg with a first section extending angularly out from the wall portion of the channel, and a second section extending out from the second wall of the channel. A chain bolt connector is inserted into a provided hole in the first plate section with the chain wrapped around the leg of the drilling platform and end chain links then inserted into a keyhole in the second plate extension and locked in by a movable plate. The nut bolt is then tightened to secure the apparatus against the leg of a platform. A set screw makes contact with the platform leg to complete the cathodic protection circuit. The clamp apparatus can support a single anode or a double anode or be utilized as a riser clamp on the leg of a drilling platform in order to prevent corrosion of the platform leg.
The adjustable chain allows the single clamp apparatus to be adjustably affixed to platform legs even when encrusted with marine growth, protective coatings, or like diameter changes of the normal leg diameter. The rise of various U-clamps to fit particular leg sizes is eliminated as is the need for mechanical removal of such encrusted or coated material on the platform legs, risers, and the like.
The present invention thus provides a clamp apparatus which is light, easily secured against the leg of a platform without the need for mechanical removal of encrusted marine growth and in most cases by a single diver. Presently, two or three divers are required per prior art type clamp while several or three clamps could be secured on the platform leg at one time reducing the time involved significantly and the expense also.
It is therefore one object of the apparatus of the present invention to provide a clamp means for securing against the leg of a drilling platform which is lightweight and easily and compactly moved about from point of origin to point of designation.
It is another object of the apparatus of the present invention to provide a clamp apparatus for securing against the leg of a drilling platform which is lightweight and can be attached to the platform leg by the use of a single diver.
It is another object of the apparatus of the present invention to provide a clamp means through which a single anode or double anode or riser can be secured to the leg of a drilling platform, the use of a single chain being wrapped around the leg of the platform and secured tightly around that leg.
It is another object of the apparatus of the present invention to provide a clamp means for securing a clamp against the leg of a drilling platform which is so constructed so that the clamp may be secured against various diameter pipes while maintaining its secure position against whatever diameter size pipe it is set against.
Yet another object of the present invention is to provide a clamp apparatus which has an adjustability, allowing attachment to various diameter platform legs, even those encrusted with marine growth and the like.